The determination by arbitrators of the law applicable to the merits of the case in the absence of express choice by the parties continues to be one of the biggest difficulties of international arbitration. The variety of choice of law methods and the wide discretion given to arbitrators by arbitration laws and rules means that parties can never predict what law will be applied to solve their dispute. A uniform and prescriptive method is urgently needed. Critically evaluate this statement, referring to relevant laws and materials as appropriate.